This grant application is designed to investigate the role of T lymphocytes in the genesis of the cutaneous lesions of lupus erythematosus. Our previous work investigating the role of immunoglobulins and complement has demonstrated a complete lack of association between the presence of immunoglobulins and complement deposition in the skin of lupus erythematosus patients and the presence or absence of cutaneous lupus. The histologic features of the discoid lupus and the typical butterfly rash reveal the presence of a mononuclear infiltrate hugging the dermal-epidermal junction. Polymorphonuclear leukocytes, a common feature of an antibody complement mediated disease is distinctly unusual in these lesions. We propose to investigate the possible role of T cell in the pathogenesis of cutaneous lupus lesions by 1) creating an animal model employing guinea pigs. The guinea pigs will be sensitized to various forms of DNA (single stranded DNA, native DNA and ultraviolet denatured DNA). The sensitization will be accomplished by foot pad injections of these various fractions of DNA coupled to methylated bovine serum albumin. The animals will be examined for in vivo cell mediated type immune response to the DNA fraction. The lymphocytes will also be checked in vitro for their ability to respond to these antigens. 2) Discoid lupus patients as well as those with systemic lupus erythematosus will also be examined for their peripheral lymphocyte's ability to respond to these various fractions of DNA. This response will be measured by the incorporation of tritiated thymidine.